Internal combustion engines (ICE) for motor vehicles generally include a cylinder block that defines at least one cylinder accommodating a reciprocating piston coupled to rotate a crankshaft. The cylinder is closed by a cylinder head that cooperates with the reciprocating piston to define a combustion chamber. A fuel and air mixture is cyclically drawn into the combustion chamber and ignited, thereby generating hot expanding exhaust gasses that cause the reciprocating movements of the piston. Cylinder blocks of internal combustion engines are subjected to high bending and torsion forces and therefore an improved strength and rigidity of the block is desired.
A known cylinder block has a series of diagonal ribs on its sidewalk, the diagonal ribs crossing each other at an angle with respect to an axial direction defined by a crankshaft. In the known cylinder block, a first group of diagonal ribs is provided, each rib of the first group ranging from a position approximately corresponding to a cylinder partition wall at the upper part of the side wall of the cylinder block to a position approximately corresponding to a cylinder center in a lower portion of the cylinder block approximately corresponding to the base of a cylinder. A second group of diagonal ribs is provided, each rib of the second group of ribs ranging from a position approximately corresponding to the cylinder center at the upper part of the side wall of the cylinder block to a position approximately corresponding to the base of a cylinder, the diagonal ribs of the second group being inclined in a different direction with respect of the diagonal ribs of the first group.
A transverse rib is also provided so that it may intersect in points where the ribs of the first and of the second group intersect forming a triangular pattern composed of isosceles triangles. Internally to some of the triangles of the triangular pattern, in positions corresponding to the cylinder partitions, couples of cylindrical portions are provided.